/// <summary>
/// Gets the element at the specified index.
/// </summary>
/// <remarks>Used for pre-R 3.5 </remarks>
/// <param name="index">The zero-based index of the element to get.</param>
/// <returns>The element at the specified index.</returns>
protected override string GetValue(int index)
{
int offset = GetOffset(index);
IntPtr pointerItem = Marshal.ReadIntPtr(DataPointer, offset);
if (pointerItem == Engine.NaStringPointer)
{
return(null);
}
IntPtr pointer = IntPtr.Add(pointerItem, Marshal.SizeOf(typeof(Internals.PreALTREP.VECTOR_SEXPREC)));
return(InternalString.StringFromNativeUtf8(pointer));
}
private string ReadString(IntPtr pointer, int offset)
{
pointer = Marshal.ReadIntPtr(pointer, offset);
if (Engine.Compatibility == REngine.CompatibilityMode.ALTREP)
{
pointer = GetFunction <DATAPTR_OR_NULL>()(pointer);
}
else
{
pointer = IntPtr.Add(pointer, Marshal.SizeOf(Engine.GetVectorSexprecType()));
}
return(InternalString.StringFromNativeUtf8(pointer));
}
/// <summary>
/// Gets the element at the specified index.
/// </summary>
/// <remarks>Used for R 3.5 and higher, to account for ALTREP objects</remarks>
/// <param name="index">The zero-based index of the element to get.</param>
/// <returns>The element at the specified index.</returns>
protected override string GetValueAltRep(int index)
{
// To work with ALTREP (introduced in R 3.5.0) and non-ALTREP objects, we will get strings
// via STRING_ELT, instead of offseting the DataPointer. This lets R manage the details of
// ALTREP conversion for us.
IntPtr objPointer = GetFunction <STRING_ELT>()(this.DangerousGetHandle(), (IntPtr)index);
if (objPointer == Engine.NaStringPointer)
{
return(null);
}
IntPtr stringData = GetFunction <DATAPTR_OR_NULL>()(objPointer);
return(InternalString.StringFromNativeUtf8(stringData));
}
/// <summary>
/// Gets the element at the specified index.
/// </summary>
/// <remarks>Used for R 3.5 and higher, to account for ALTREP objects</remarks>
/// <param name="index">The zero-based index of the element to get.</param>
/// <returns>The element at the specified index.</returns>
protected override string GetValueAltRep(int index)
{
// To work with ALTREP (introduced in R 3.5.0) and non-ALTREP objects, we will get strings
// via STRING_ELT, instead of offseting the DataPointer. This lets R manage the details of
// ALTREP conversion for us.
IntPtr objPointer = GetFunction <STRING_ELT>()(this.DangerousGetHandle(), (ulong)index);
if (objPointer == Engine.NaStringPointer)
{
return(null);
}
IntPtr stringData = IntPtr.Add(objPointer, Marshal.SizeOf(typeof(Internals.ALTREP.VECTOR_SEXPREC)));
return(InternalString.StringFromNativeUtf8(stringData));
}
private string ReadString(IntPtr pointer, int offset)
{
pointer = Marshal.ReadIntPtr(pointer, offset);
pointer = IntPtr.Add(pointer, Marshal.SizeOf(Engine.GetVectorSexprecType()));
return(InternalString.StringFromNativeUtf8(pointer));
}
private string ReadString(IntPtr pointer, int offset)
{
pointer = Marshal.ReadIntPtr(pointer, offset);
pointer = IntPtr.Add(pointer, Marshal.SizeOf(typeof(VECTOR_SEXPREC)));
return(InternalString.StringFromNativeUtf8(pointer));
}
